(1) Field of the Invention
The present invention relates to an improvement in a package for containing a semiconductor element.
(2) Description of the Related Art
A conventional package for containing a semiconductor element, especially a glass-sealed semiconductor container package sealed by fusion bonding of a glass, comprises an insulating vessel having in the interior thereof a space for containing a semiconductor element, which comprises an insulating vessel and a lid member, and an external lead terminal for electrically connecting the semiconductor element contained in the vessel to an external electric circuit. In this package, a sealing glass material member is attached to each of confronting main surfaces of the insulating substrate and lid member, the external lead terminal is fixed to the main surface of the insulating substrate, respective electrodes of the semiconductor element are wire-bonded and connected to the external lead terminal and the glass material members fusion-bonded to the insulating substrate and lid member are melted and integrated to seal the semiconductor element in the interior air-tightly.
In the conventional glass-sealed semiconductor element container package, the external lead terminal is composed of an electroconductive material such as KOVAR (an alloy comprising 29% by weight of Ni, 16% by weight of Co and 55% by weight of Fe) or 42 Alloy (an alloy comprising 42% by weight of Ni and 58% by weight of Fe), but since Koval or 42 Alloy has a high permeability and a low electroconductivity, Koval or 42 Alloy has defects as described below.
(1) KOVAR or 42 Alloy consists solely of ferromagnetic metals such as iron (Fe), nickel (Ni) and cobalt (Co), and the permeability is as high as 250 to 700 (CGS). Accordingly, if an electric current flows in the external lead terminal composed of KOVAR or 42 Alloy, a large self-inductance proportional to the permeability is generated in the external terminal and this large self-inductance indues a counter electromotive force as a noise, and this noise is put into the semiconductor element to cause the semiconductor element to make a malfunction.
(2) KOVAR or 41 Alloy has such a low electroconductivity as 3.0 to 3.5% (IACS). Accordingly, when a signal is transmitted through the external terminal composed of Koval or 42 Alloy, the signal-transmitting speed is extremely low and a semiconductor element of the high-speed driving type canno be contained.
(3) With increase of the density and integration degree of the semiconductor element to be contained in the semiconductor container package, the number of electrodes of the semiconductor elements increases drastically, and the width of the external lead terminal for connecting respective electrodes of the semiconductor element to the external electric circuit is much reduced. Because of this reduction of the width of the external lead terminal as well as the low electroconductivity of KOVAR or 42 Alloy described in (2) above, the electric resistance becomes very large. When a signal is transmitted through the external lead terminal, because of this large electric resistance of the external lead terminal, the signal is greatly attenuated, and it is impossible to put the signal precisely into the semiconductor element contained in in the interior and a malfunction is caused in the semiconductor element.